1. Field of the Invention
This invention relates to a composite, impact diverting and force dissipating hip arthroplasty prosthesis characterized by greatly enhanced biocompatibility and wear resistance, wherein potentially damaging shear forces, which are normally transmitted directly to living bone cells through a conventional hard metal arthroplasty prosthesis, are dampened, softened, diverted and non-linearly decelerated before being transmitted to the relatively delicate living bone cells.
2. Prior Art
The conventional hip arthroplasty prosthesis is usually formed from stellite, vitalium, titanium, or the like, acetabular and subtrocanteric elements. Intraskeletal impact forces generated by patient movement are directly transmitted from the pelvis through a conventional arthroplasty prosthesis to a plane of force concentration located at the contact surface between the hard, metallic prosthesis and the relatively soft living bone. Continued impact trauma may induce osteoarthritis or osteomyelitis. Pre-existing osteoporosis may also be aggravated which, in turn, may necessitate explant of the arthroplasty prosthesis and undesirable arthrodesis of the hip joint.
More particularly, with conventional hard metal hip arthroplasty prosthesis, equal and opposite forces are generated by the arthroplasty prostheses in response to applied, vertical intraskeletal loads. Such opposing forces produce parallel shear planes which may undesirably exceed the fatigue strength of bone cement fixation procedures or cause scission of stabilizing tissue ingrowth between the patient's bone and the conventional hip arthroplasty protheses. The failure of the conventional hip arthroplasty protheses to effectively divert, dissipate or absorb intraskeletal loads reduces the biocompatibility, longevity and patient comfort of such arthroplasty protheses.